Jesse Eisenberg never really planned to pursue an acting career—it found him.

"I lucked into things that I never expected," says Eisenberg, 25, about the breadth of his impressive résumé, which includes the critically acclaimed films Roger Dodger, The Squid and the Whale, and, most recently, Adventureland. "I never planned for any of it. It just happened despite my intentions."

When Eisenberg was 13, an agent discovered him doing community theater near his New Jersey home. The agent suggested that Eisenberg audition for a Broadway production of Summer and Smoke. He won the part of an understudy and ultimately took over the role. "It really was an exciting experience," he recalls. "But I had no idea who Tennessee Williams was. You can't appreciate him at that age."

A few years later when he was a student at New York's High School of Performing Arts, he was asked to do a reading of Roger Dodger at the downtown Nuyorican Poets Café and then enlisted to be in the film. Centered around a charming cad (Campbell Scott) who spends a drunken evening carousing with his teenage nephew (Eisenberg)—tutoring him on scoring women—the film became an indie classic and an Independent Spirit Award winner. "They did readings every Monday for years at this café, and maybe two of the movies read there actually got made," says Eisenberg.

"And not only did it get made, they didn't audition other actors for my part." But aside from having good luck, Eisenberg is extraordinarily talented and exceptionally modest, especially when talking about his craft. "It's hard to objectively evaluate yourself," he says. "Acting is a visceral process." In The Squid and the Whale, Noah Baumbach's rich autobiographical film about the unraveling of his family, Eisenberg plays Walt Berkman to pitch-perfect effect. Walt is articulate beyond his years yet heartbreakingly insecure. "When I read the script, I loved it so much and felt so close to it," says Eisenberg. "Personal stories are the most desirable projects to work on as an actor. They feel lived-in and the most authentic. The characters are rich because they're based on real people."

In Adventureland, which opened Friday, Eisenberg stars with Kristen Stewart in Greg Mottola's semiautobiographical coming-of-age tale about finding love in the most unlikely of places. As with The Squid and the Whale, Eisenberg was instantly drawn to the script and depth of the characters. "It's so sweet and told so well," he says. In the 1980s, Mottola spent a summer working at a ramshackle amusement park, similar to the one in the film. Mottola based elements of Eisenberg's character, James Brennan, on himself. "I love the character so much and never thought that I would get chosen to play the part," says Eisenberg, who didn't have to audition for this one either. "James is such a wonderful well-rounded person, which is exciting." Eisenberg seamlessly maintains his earnestness and sincerity in the midst of the film's comic environment, rather than forcing the funny. "I let it come from a real place."

While Eisenberg's films have gotten a fair bit of attention, he finds all the interest in him a little odd. "Being recognized is a jarring thing. It feels weird," says the actor. "You think, Is it a good thing? And if it's a good thing, do I deserve it? And then you feel unworthy. And then you say why am I not worthy?"

Eisenberg prefers living a bit more anonymously in New York City, where he says people care less about the entertainment industry, and he can go to school virtually without being recognized. "California is so much more integrated with that culture on a daily basis," he says. He admires his Adventureland costar Kristen Stewart for how she manages her mega-success. "She's so smart and mature and handles it so beautifully and respectfully. She is a really good actress, appreciates good movies, and is smartly using Twilight success to do some smaller movies."

Who else does Eisenberg admire? If he weren't an actor, he could see himself as a teacher. "My father is one, and I would love to do that as well," says Eisenberg, whose girlfriend is also in the profession (he is fairly tight-lipped about her though). "The people who are closest in my life are all teachers. It feels so good that you're having an influence on kids."

During his own school years in Queens and then New Jersey, Eisenberg saw acting in community theater as a means to escape. "I didn't fit in. And this gave me an outlet, so I didn't have to hang with kids after school because I had a rehearsal," explains Eisenberg. "Acting gave me an excuse to separate from the social things that made me uncomfortable." His first part was in the chorus of the musical hybrid Annie and Oliver. "They couldn't get the rights to Oliver," he recalls. "So they combined the shows Annie and Oliver, where the two orphans find each other."

Staying close to his early thespian roots, Eisenberg continues to do theater. Most recently, he co-starred in Lucy Thurber's Scarcity off Broadway at the Atlantic Theater Company. Eisenberg played a 16-year-old math genius desperate to flee his seriously dysfunctional family. "Lucy writes these really eccentric people," he says. And it seems that theater is a more natural forum for Eisenberg, who doesn't particularly crave the attention that comes with fame. When he's not on location, Eisenberg lives a very low-key life in Manhattan, studying anthropology at the New School. His great passion is riding his bicycle everywhere. ("You can cover so much territory so quickly. It takes 25 minutes to go from Chelsea to the Upper East Side on a bike. But if you take the subway, it's like 45 minutes.") Eisenberg's course load is as important as his film roles. "My dad is a college sociology professor, so there was an emphasis on academics growing up," he says. "The school offers these weird courses that seem unrelated to each other and so diverse." Last semester he took classes about food, reading author Michael Pollan's In Defense of Food.

Eisenberg hopes to return to school in the summer, but work has kept him busy. "I've been working basically every day for the past six months," he says. "But everybody in my classes has jobs they have to balance." He is making Zombieland in Georgia with Woody Harrelson about a postapocalyptic world overrun by zombies. Eisenberg plays Flagstaff, who joins forces with the few remaining human survivors. "It's a very clever and creative film," says the actor. "The characters don't have names but are given names of the cities they are from. They need to remain emotionally distant in case they have to kill one other."

With the upcoming film Holy Rollers, based on a true story, he's a Hasidic youth from Borough Park, Brooklyn, who becomes an ecstasy courier in the late 1990s. "It's not a drug movie," says Eisenberg. "It is told realistically with my character's conflict between his faith and the modern world." Eisenberg enlisted his real-life little sister, Hallie Kate Eisenberg (The Insider), a talented actress in her own right, to play his on-screen one. "With such a small movie, everyone had to pool the resources they had access to," Eisenberg says. "And she was so sweet to do it." He's also signed on to play poet Allen Ginsberg in the upcoming Kill Your Darlings. "These great opportunities come before I anticipate them," he says. "That's the nature of the industry."

Working with such good material has inspired Eisenberg to write a musical, some plays, and a novel, which he's currently finishing. "When you're working 14 hours a day on something really good, you start to embody the artistry of the writing, and that's a great influence," he explains. He writes every night, before he goes to sleep. In fact when asked about his dream role, he says he'd like to do some of the work he's written. "I've spent so much time with it." As unusual as his films, his plays are about "the hubris of young bigots." In one, a young American man goes to Poland to stay at his second cousin's house. She's a 75-year-old Polish woman, and he has absolutely no respect for her. "It is a kind of true story. I went to Poland to stay with my second cousin," he says. And then Eisenberg pauses, "But I wasn't mean to her."